function getRandomColor(flag = true) {
    if (flag) {
        let str = '#'
        let arr = ['0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f']
        for (let index = 1; index <= 6; index++) {
            let random=Math.floor(Math.random()*arr.length)
            str += arr[random]
        }
        return str
    } else {
        let r = Math.floor(Math.random()*256)
        let g = Math.floor(Math.random()*256)
        let b = Math.floor(Math.random()*256)
        return `rgb(${r},${g},${b})`
    }
}

console.log(getRandomColor(false));